Design, synthesis, and assembly of composite liquid crystal elastomer fibers

非技术总结：软材料可以在外部刺激下显著改变尺寸，形状，从二维（2D）到三维（3D），体积和物理性质，具有广泛的潜在应用前景。植物可以通过细胞壁的预编程各向异性变形来实现复杂的响应变形，细胞壁由不同刚度的纤维聚合物分层排列而成。本项目旨在通过编程纤维聚合物的各向异性来模拟细胞壁的结构和功能，同时探索生物学中普遍存在的分子异质性和相分离。该研究将促进聚合物科学与工程、软物质物理和机械工程学科之间的协同作用，以开发复杂的、多组件的、多阶段的网络。该研究成果将在下一代智能传感器、执行器、软机器人、智能可穿戴设备、3D显示器等领域具有潜在的应用前景。它还将成为招聘和培训各级学生的有效工具。将特别强调代表性不足的群体在校园进行研究。最新的研究成果将在费城材料日和宾夕法尼亚大学科学咖啡馆项目上展示。聚合物网络的形状变形和重塑将为激发公众的兴趣创造一个重要的拓展机会，从而激发和吸引人们对科学、技术、工程和数学（STEM）的兴趣。将组织研讨会，以展示研究成果，并促进与来自学术，工业和国家实验室的研究人员的互动。技术概述：计划中的研究是基于多管齐下的活动，包括设计、合成、组装、制造、表征和一套独特的环境响应聚合物的性能优化。这些是液晶弹性体和纤维形式的复合材料，具有精确控制的成分、分子取向、结构和从纳米到宏观尺度的机械响应。重要的是，这项研究将为如何在分子水平上动态配置材料的内在特性提供一个整体的观点，即化学成分、相分离和交联梯度，同时以圆柱形约束的形式保持微观到宏观尺度上的几何控制。多组分、多相网络将拓宽材料的选择范围，以创造更复杂的结构，并精确控制材料弹性的各向异性。响应外部刺激的复杂形状将被创造出来，以模仿植物细胞壁的结构和功能，并具有可调谐的光子颜色和机械适应性等附加功能。研究成果将丰富将局部可控自由度与全局几何、形状和变形路径联系起来的基础知识。这些见解可能有助于开发下一代复合纤维，用于智能传感器、执行器、3D显示器、软机器人和智能纺织品等潜在应用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY:Soft materials that can dramatically change size, shape from two-dimensional (2D) to three-dimensional (3D), volume, and physical properties in response to external stimuli are of great interest for a wide range of potential applications. Plants can achieve complex responsive morphing via a pre-programmed anisotropic deformation of cell walls, which are made of hierarchically arranged fibrous polymers of different stiffness. This project aims to mimic the cell wall structures and functions by programming the anisotropy in fibrous polymers, while exploring molecular heterogeneity and phase separation that are ubiquitous in biology. The research will foster synergistic interactions across disciplines of polymer science and engineering, soft matter physics, and mechanical engineering to develop complex, multi-component, multi-phased networks. The research outcome will lead to potential applications in next generation smart sensors, actuators, soft robots, smart wearables, and 3D displays. It will also act as an effective tool to recruit and train students at all levels. Special emphasis will be given to underrepresented groups to carry out research on campus. The latest research results will be showcased at the Philadelphia Materials Day and Penn Science Café Program. Shape morphing and reshaping of the polymer networks will create a significant outreach opportunity to excite the general public, thereby provoking and engaging interest in Science, Technology, Engineering, and Mathematics (STEM). A symposium will be organized to feature research outcome and facilitate interactions with researchers from academic, industrial and national labs.TECHNICAL SUMMARY:The planned research is based on multi-pronged activities, including design, synthesis, assembly, fabrication, characterization, and property optimization of a unique set of environmentally responsive polymers. These are liquid crystal elastomers and their composites in the form of fibers with precisely controlled compositions, molecular orientations, architectures and mechanical responses from nano- to macroscales. Importantly, the research will offer a holistic view on how to dynamically configure the material’s intrinsic properties at the molecular level, that is chemical composition, phase separation, and crosslinking gradient, while keeping sights of geometric controls at the micro- to macroscale in the form of cylindrical confinement. The multi-component, multi-phased networks will broaden the materials palette to create more complex structures with precisely controlled anisotropy in material elasticity. Complex shapes in response to an external stimulus will be created to mimic plant cell wall structures and functions, with bonuses such as tunable photonic colors and mechanical adaptivity. The research outcome will enrich fundamental knowledge that relates the locally controllable degrees of freedom to the global geometries, shapes and shapeshifting paths. The insights could contribute to the development of the next generation composite fibers for potential applications such as smart sensors, actuators, 3D displays, soft robots, and smart textiles. .This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.